The RASPLAV project aimed to refine accident management strategies during a reactor core meltdown; it was completed in June 2000. Little is known about the complex interactions that take place during a core meltdown, so one of the RASPLAV project's primary goals was to develop an understanding of this process. The information gathered during tests at the Kurchatov Institute have allowed scientists to develop models of a core meltdown. These models can be used in the design of new reactors and in refining the accident procedures for existing ones.

Two aspects of the issue were considered. First, for existing reactors, where external cooling may not be practicable, the process and time sequence before melt-through were studied. This was to help devlop management strategies for severe accidents. Secondly, for future and some existing reactor designs, the project aimed to determine the heat transfer conditions under which cavity flooding can be a viable accident management option.

The project was run in two successive phases. The RASPLAV Phase-2 project investigated the progression of a severe accident and in particular the thermal loading imposed by a corium pool on the lower head of a light water reactor (LWR) vessel. It followed an earlier Phase-1 project dedicated mainly to the build-up of the experimental and analytical infrastructure.

The project objectives were to obtain relevant data on the physical and thermal behavior of the corium in large-scale tests, to derive thermal-physical property data for various molten core materials, and to investigate the effects of stratification of molten materials. The programme of work involved the use of the large facilities available at the Kurtchatov Institute in Russia. Four large-scale tests were carried out and were complemented by a series of smaller-scale experiments, all involving the use of materials representative of power reactor cores. Experiments with these test materials in molten condition required temperatures of approximately 3000 deg.C - a very challenging task, especially for large-scale tests. The analytical work was done at the Russian Academy of Science's Institute of Nuclear Safety (IBRAE).

The project was successfully concluded in 2000.The results are set out in the Project final report which was presented and reviewed in November 2000 at the last RASPLAV seminar, sponsored by the OECD and hosted by the German Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS), Munich. The project data remained proprietary until 2003.